Atlantic Rhododendron and Horticultual Society (ARHS) -
Their Mission Statement:states that the 'ARHS supports and promotes
the development and exchange of expertise and material relating
to the practice of creating and maintaining year-round garden
landscapes featuring rhododendrons and other plants'.

North American Rock Garden Society (NARGS) - NARGS
is for gardening enthusiasts interested in alpine, saxatile,
and low-growing perennials. It encourages the study and cultivation
of wildflowers that grow well among rocks, whether such plants
originate above treeline or at lower elevations. Through its
publications, meetings, and garden visits, NARGS provides
extensive opportunities for both beginners and experts to
expand their knowledge of plant cultivation and propagation,
and of construction, maintenance, and design of special interest
gardens. Woodland gardens, bog gardens, raised beds, planted
walls, container gardens, and alpine berms are all addressed."

Canadian
Chrysanthemum & Dahlia Society - The
C.C.D.S.is affiliated with U.K. and U.S. National Chrysanthemum
and Dahlia Societies and was formed in 1965 to promote the
cultivation of chrysanthemums and dahlias, and to develop
the friendship that goes with it.

Cactus
and Succulent Society of America - the CSSA is a
society devoted to earning to understand and care for succulent
plants at home and in the wild through education, conservation
and research.